. The Biochemical journal. Biochemistry. 17(» S. S. ZILVA "'I tlic ;illilli;ils. One of tlic mis It-It mi |||;|| dirl (|r\ clniicd \c|((|i||| Ii;i Imia iiiid ilicil al'lcr jilioiit (i weeks. Wlicii the exposed l»iilter was replaced by unexposed l)iilter kept for (J hours at '.]')" in llie diet of the remaiiiin*,' two mt-H they at once comnieiu'ed niow iiii:. thus showiiiii; that the fat-soluble A was supplitMl by the addition of the unexposed l)ut. not l)y the exposed ])utter. The lat-Holuble .1 faetoi- in the butter was therefore inactivated by exposure to the uItra-\iolet ia\ 2
. The Biochemical journal. Biochemistry. 17(» S. S. ZILVA "'I tlic ;illilli;ils. One of tlic mis It-It mi |||;|| dirl (|r\ clniicd \c|((|i||| Ii;i Imia iiiid ilicil al'lcr jilioiit (i weeks. Wlicii the exposed l»iilter was replaced by unexposed l)iilter kept for (J hours at '.]')" in llie diet of the remaiiiin*,' two mt-H they at once comnieiu'ed niow iiii:. thus showiiiii; that the fat-soluble A was supplitMl by the addition of the unexposed l)ut. not l)y the exposed ])utter. The lat-Holuble .1 faetoi- in the butter was therefore inactivated by exposure to the uItra-\iolet ia\ 2 3 4 5 6 7 8 9 10 1112 Fig. -1. The first perpendicular dotted line marks the time at which the administration of tJic exposed butter commenced and the second line that of the unexposed butter. On exposing the butter to the ultra-violet rays by means of the technique described above tw^o other factors are introduced which might be suspected to bring about the inactivation of the fat-soluble A factor, namely, {a) tem- perature and (b) ozone, which, as is well known, is produced by the action of ultra-violet light on the atmospheric oxygen. That the slight eleva- tion of the temperature of the butter is not responsible for the inactivation is seen from the above experiment, as the addition to the diet of butter not exposed to the ultra-violet light but kept for 6 hours at 35° at once induces grow^th. The part played by the ozone in the inactivation of the factor, as well as the chemical changes produced by the ultra-violet light in the fat, are now being studied. In this connection it is of interest to add that it has been previously pointed out by many investigators that the sterilisation of milk by means of ultra-violet rays imparts to the milk a peculiar taste. This is no doubt due to the alteration in the butter fat brought about by the exposure. In view of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readab
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbiochem, bookyear1920
